1. Field of the Invention
The present invention relates to a device holding apparatus preferably used for an electric device testing apparatus for testing a variety of electric devices, such as semiconductor integrated circuit element (hereinafter, referred to representatively as ICs).
2. Description of the Related Art
A testing apparatus for testing a finally produced device, such as an IC chip, is necessary in a producing process of a semiconductor device, etc. As one kind of such testing apparatuses, an electric device testing apparatus for testing an IC chip under applying a thermal stress of a normal temperature, a higher temperature and a lower temperature than a normal temperature is known. It is because IC chips are required to guarantee as a feature thereof to operate well under a normal, high and low temperature.
In this kind of an electric device testing apparatus, a test is conducted after a large number of pre-test IC chips loaded on a customer tray are reloaded on a test tray conveyed in the testing apparatus, and tested IC chips are reloaded to customer trays of different categories in accordance with the test result. A device holding apparatus called pick-and-place is used for such a reloading operation of IC chips.
There is known a device holding apparatus of the related art using a vacuum suction force wherein a rubber pad is used for absorbing impacts device errors and in a portion contacting an IC chip.
However, in a testing apparatus of a type conducting the reloading operation of IC chips in a low temperature chamber, an error in picking up an IC chip was liable to occur due to the rubber pad becoming hard in the low temperature environment. Also, there has been a disadvantage that static electricity charged in an IC chip cannot be removed when the IC chip contact portion was comprised of an insulator like rubber, etc.
Accordingly, adoption of a highly conductive metal pad was considered, however, an impact by a metal pad becomes large at the time of contacting an IC chip and the IC chip is liable to be damaged, so a speed of approaching to the IC chip had to be slower to prevent this, and it has been a bottleneck of the reloading operation at a higher speed.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
An object of the present invention is to provide a device holding apparatus excelling in an effect of removing static electricity and an effect of preventing damages on devices.
(1) According to a first aspect of the present invention, there is provided a device holding apparatus, comprising a base plate; a hollow pad guard provided on the base plate; a pad pin inserted to the pad guard movably in an axis direction and having a through hole; a pad provided at a tip of the pad pin and having a through hole connected to the through hole of the pad pin; and a bellows pad provided on the base plate, having a through hole connected to the through hole of the pad pin and being elastic in the axis direction; for holding by suction a device by the pad by applying a negative pressure to the through hole of the bellows pad, the through hole of the pad pin and the through hole of the pad.
In this device holding apparatus, a pad is approached to a device to contact, and in this state, a negative pressure is applied to a through hole of a bellows pad, a through hole of a pad pin and a through hole of a pad. As a result, the device is sucked by the pad, and at the same time, the bellows pad is shrank due to the negative pressure applied to the through hole and the device is sucked and picked up together with the pad and the pad pin.
In the present invention, a force acting on the device at the time of bringing the pad close to the device to contact is only own weights of the pad and the pad pin and an elastic force of the bellows pad. Accordingly, even when the pad approaches at a high speed, the force acting on the device is small and possibility of damaging the device becomes small. Furthermore, since the force acting on the device is small, the pad can be comprised of conductive metal materials and an effect of removing static electricity is large.
Note that when releasing the device, the negative pressure having been applied to the through hole of the bellows pad, through hole of the pad pin and through hole of the pad until then is stopped, or a positive pressure is brought to act to the contrary. As a result, the bellows pad having been shrank until then is stretched and the pad and the pad pin are lowered and the device is released.
(2) According to a second aspect of the present invention, there is provided a device holding apparatus comprising a base plate; a hollow pad guard provided on the base plate; a pad pin inserted to the pad guard movably in an axis direction and having a through hole; a pad provided at a tip of the pad pin and having a through hole connected to the through hole of the pad pin; and an elastic body provided between the base plate and the pad pin for giving to the pad pin a force in its tip direction; and a sealing body for forming an airtight chamber on a base end side of the pad pin; for holding by suction a device by the pad by applying a negative pressure to the airtight chamber, the through hole of the pad pin and the through hole of the pad.
In this device holding apparatus, a pad is brought close to a device to contact, and in this state, a negative pressure is applied to an airtight chamber, a through hole of a pad pin and a through hole of a pad. As a result, the device is sucked by the pad, and at the same time, an elastic body is shrank due to the negative pressure applied to the through hole and the device is sucked and picked up together with the pad and the pad pin.
In the present invention, since the pad and the pad pin are provided on a base plate via the elastic body, it is possible to surely hold a device by suction without using a rubber pad and it becomes particularly suitable to a use in a low temperature environment.
Also, a force acting on the device at the time of bringing the pad close to the device to contact is only own weights of the pad and the pad pin and a reacting force of the elastic body. Accordingly, by suitably adjusting an elasticity coefficient of the elastic body, the force to be acted on the device is small even if the pad approaches at a high speed, and the possibility of damaging the device becomes less. Furthermore, since the force acting on the device is small as such, the pad can be comprised of conductive metal materials and an effect of removing static electricity is large.
Note that when releasing the devices, the negative pressure having been applied to the airtight chamber, through hole of the pad pin and through hole of the pad until then is stopped, or a positive pressure is brought to act to the contrary. As a result, the elastic body having been shrank until then is stretched and the pad and the pad pin were lowered and the device is released.
(3) It is not particularly limited in the above invention, but it is preferable that a tip of the pad is more protruding than that of the pad guard when the negative pressure is not applied.
Also, it is not particularly limited in the above invention, but it is preferable that the pad, pad pin and base plate are comprised of a conductive material.
Alternately, instead of this, it is more preferable that the pad guard is comprised of a conductive material and the device contacts the tip of the pad guard when the negative pressure is applied.
It is not particularly limited in the above invention, but the pad pin preferably comprises a rotation stop mechanism. An angle of a held device is aligned by the pad pin because of the provision of the rotation stop mechanism to it.